Drying-stove.



UNITED STATES PATENT OFFICE.

DRYING-STOVE.

Specification of Letters Patent.

Patented Aug. 2'7, 1907.

Application filed April 22,1907. Serial No. 369,606.

To all whom it may concern:

Be it known that I, PAUL OSTERTAG, a citizen of Switzerland, residing atWinterthur, in the canton of Zurich, Switzerland, have-invented certainnew and useful Improvements in Drying-Stoves; and I do hereby declarethe following to be a full, clear, and exact description of theinvention, such as will enable others skilled in the art to which itappertains to make and use the same.

The subject-matter of the present application is an improveddrying-stove of the multiple-story type for drying coal and othermaterial which while in a wet condition is able to stand considerableheat, but to which as the drying operation advances only slight warmthshould be supplied if the ignition of the ma terial is to be avoided.

The new stove is built after the manner of the wellknown stoves oi themultiple-story type, that is, it possesses several floors in the form oftrays or plates which are arranged one above another and are carried bya rotating central hollow shait together with which the floors slowlyrotate. The material to be dried is brought on to said floors insuccession which lead it round in the stove which incloses them and thusbring it into contact with the drying medium.

N ow the object of the present invention is to render stoves of theabove-described type applicable to the drying of the materials mentionedabove particularly by forming each of the upper drying-chambers orstoving-chambers containing the wetter portions of the material to bedried as a closed channel in which a fixed radial partition-wallreaching from the outer wall of the stove up to the hollow shaft isarranged, and by not only the material to be dried but also thedrying-medium for each stoving-chamber being introduced separately intosaid channels, so that the drying medium is compelled to traverse theseannular stoving-chambers up to the outlet situated at the other side ofthe partition wall in the direction of retation of the floors, that is,in the same direction as that in which the material to be dried lying onsaid floors moves,'and so that, while the freshly delivered Wet materialfor the time being is heated most in these upper stoving-chambers, thelower stoving chambers, into which the material does not pass until ithas been almost completely dried, are in communication with the outerair through holes in the stove wall and with the interior of the shaftcarrying the floors through holes in the periphery of said shaft, theresultv of which is that fresh cold air can be led through the lowerchambers for the purpose of cooling the material undergoing treatment.

One form of the drying-stove constructed according to this invention isillustrated by way of example, in the accompanying drawing, in which:

Figure 1 is a vertical section on the line B-B Fig.

2, and Fig. 2 is a horizontal section on the line A-A Fig. 1.

The stove illustrated possesses by way of example, four circular floors1, 2, 3, .4, which are situated one above another and are fitted in thestove together with a central hollow cylinder or shaft 5; with whichthey can be set in slow rotation. The whole rotating portion of thestove rests on rollers 6, the bearing 7 serving merely for centeringsaid portion. This rotating portion is driven from the shaft 9 throughthe gearings 8, 8.

Of the four floors the two upper ones 1 and 2 serve for the dryingoperation, while the others serve for cooling the dried material, whichis led round in the annular chamber formed on each story between theinner hollow cylinder 5 and the outer stove-wall 10. In the storiesabove the floors 1 and 2 the cylinder 5 is covered with fireproofmaterial. At one place on each of said stories a partition wall 11 or 12crossing the annular chamber projects from the outer wall towards thecylinder. The two supplies of furnace gasesutilized for the dryingoperation in the chambers above the heated floors 1, 2 are producedseparately in the fire-chambers 13 and 14 respectively situated near thestove and are introduced directly in front of the partition-walls 11 or12 into the respective stoving-chambers. The furnace-gases consequentlypass in these annular chambers over the floors and entirely round thecylinder 5 to the outlet flue 15 (Fig. 2) behind the partition-wall. Thefloors also are driven in the same direction of rotation. Spiralconveyances 16, 17 which project from outside into the stove serve forfeeding the material to these floors 1, 2 respectively, said conveyancesdelivering the material uniformly on to the floors behind the walls 11,1.2 and distributing it thereon in such a manner that said floors arealways covered with a layer of a thickness as uniform as possible. Thewalls do not project down quite as far as the floors so that thematerial delivered by the conveyers is carried away under them when thefloors rotate, the walls at the same time serving to scrape level theupper surface of the layer of material being fed in. In this manner theclosure between the Walls11, 12 and the floors 1, 2 is sufllcientlyperfect during .the operation of the stove to prevent the furnace gasesfrom escaping under the walls into the outlet-flue 15. The material onthese two plates 1, 2 is dried by the wet material being fed by theconveyor 16 on to the upper floor 1 together with which it travels roundonce. Immediately after the material has been delivered it is playedupon by the hot furnacegases coming from the grate in the fire-chamber13, which gases continuing their course sweep continuously over thematerial always delivering up their greatest heat to fresh material. Thesupply of heat to the latter is consequently continually less incorrespondence with the advancing state of the drying operation thefurther it has traveled round the cylinder 5. The material which hasmade one revolution on the floor 1 and which is consequently half dried,is conveyed outwards shortly before it arrives back at the point ofdelivery by means of an obliquely placed scraper 18, which is, per se ofthe well-known kind, and passes through an opening 19 in the wall of thestove into the conveyer 17 situated below, by which it is delivered onto the second floor 2 on which it is again treated in the same manner asbefore with the exception that the dryingmedium for this second portionof thedrying operation is produced on the grate in the fire-chamber 14in a less quantity, and in one which can be exactly regulated, so thatif desired the supply of heat may take place according to requirementsimultaneously with the supply of cold air, the result being that theignition of the material during this phase of the drying operation canbe readily avoided.

The uppermost stoving chambers which is above the floor 1 is closedabove by means of a plate or floor 20 which is similar to the otherfloors and likewise rotates. Said floor 20 is intended to prevent theheat from escaping and the uppermost stoving-chamber from cooling downon account of the effect of the outer air on the stove-vault. At thesame time it stores up in itself a part of the intense heat in theneighborhood of the place where the furnace-gases for the topstoving-chamber enter the stove and carries it forward during itsrotation. This has the advantage that the temperature in theneighborhood of said place does not become too high. In order toincrease the capacity of said floor to store up heat, it may be coveredwith stones. Another advantage of this arrangement consists in the roofproper 21 of the stove being able to be supported in a simple manner bymeans of I-beams, an expensive vault being unnecessary. Moreover thelayer of air over this floor 20 reduces loss of heat by conduction. In amanner similar to that in which heat is supplied to the floor 20 it isalso supplied from below to the floor 1 by means of the furnace-gases inthe second stovingchambers which heat supplied to said floor 1 is alsoturned to good account by heating the material resting on said floor.All these features lead to the material in the uppermost stoving chamberbeing subjected to the greatest heat.

The material might be completely dried in the abovedescribed manner ifdesired on more than two floors or on only one floor. After beingcompletely dried it is conveyed from the last stoving-fioor 2 on to theother floors situated thereunder, for example, in the case illustratedon to the two floors 3, 4 in order to be cooled down on these. From thefloor 2 it is led to the floor 3 by being conveyed to the edge of 2 bymeans of obliquely placed blades or by means of a scraper, or the like,as in the case of the floor 1, from which edge it falls on to the floor3 through a recess 22 in the stovewall. On said floor 3 it is pushedfrom the edge towards the center by means of stirring-arms 23 fixed inthe wall and provided with blades set obliquely to a suitable degree. Onreaching the center it falls through openings 24 in the floor on to thenext lower floor 4 on which it is conveyed in a similar manner by meansof stirring-arms 23 from the center towards the edge where it passes outof the stove through one or more openings 25. This method of conveyingthe material on the floors 3, 4 is known per sc. While traveling overthese two floors 3, 4 the material is cooled by a current of airentering into the chambers above these floors through adjustableopenings 26 in the stove-wall which current of air passes throughopenings 27 in the periphery of the hollow cylinder 5 into the latterand out into the atmosphere.

Having now explained the nature of my invention I declare that what Iclaim and desire to secure by Letters Patent is:

1. In a multiple-story drying stove in combination with a central hollowshaft 5 trays or floors 1, 2, 3, 4 turning round with said shaft, ashaft 9 and gearings 8, S for turning said shaft 5 and trays 1. 2, 3, 4rollers G, a hearing 7 carrying said rotating shaft 5 and trays 1, 2, 3,4, a wall 10 surrounding said revolving shaft and trays, partition walls11. 12 respectively connected to said wall 10 and reaching into thechambers formed above the plates 1, 2 respectively. scrapers 23 heldrigidly in the wall 10 and reaching into the spaces above the plates 3,4 respectively, the whole as described and illustrated and for thepurpose set forth.

2. In drying mechanism, a central shaft and a vertical series of traysattached thereto, in combination with means for rotating said shaft andtrays. a wall surrounding said trays, feeding devices supplying theupper tray, outlet passages from each tray, a conveyer from the firsttray to the second, a scraper arranged to direct the partly driedmaterial from the first tray through its outlet to the said conveyor,and stirring arms which direct such material to the outlets of the thirdand fourth trays substantially as set forth.

3. In drying mechanism, a central shaft and a vertical series of traysattached thereto, in combination with partitions dividing the spacesabove the first and second trays, means for supplying furnace gases tosaid spaces in prox- 1 iinity to said partitions, a passage for thematerial downward from one tray to another, means for rotating theshaft, and trays and means for cooling the lower two trays for thepurpose set forth.

4-. In drying mechanism, a hollow central shaft a series of trayscarried thereby, a passage for the material acted on from tray to traydownward, means for supplying a heated drying medium to the upper trayand means for rorating the said shaft and trays, the said shaft havingits wall perforated to supply cool air to the lower part of the seriesof trays substantially as set forth.

3. In drying mechanism, an inclosed rotating shaft and verticahseries oftrays, in combination with means for supplying a heated fluid dryingagent to the upper part of said series, means for supplying a coolingfluid to the lower part of said series and means for directing theinaterial to descend in a spiral path from story to story of theapparatus substantially as set forth.

In' testimony whereof. I have signed my name to this specification inthe presence of two subscribing witnesses.

PAUL OSTER'IAG.

Witnesses It. BKAUMANN,

H. STOESSEL.

